Time to onset of oestrus after the injection of heifers with cloprostenol

When two injections of 500 microgram cloprostenol are given 11 days apart to unselected cycling heifers the onset of oestrus behaviour is significantly earlier, and more compact, after the second injection than after the first. The time from treatment to the onset of oestrus following this second injection was not significantly different from that obtaining in animals given a single injection on day 8 of the oestrous cycle. It is suggested that the more precise onset of oestrus after the second of two cloprostenol injections is due to the majority of animals being at a comparable stage of the oestrous cycle when the treatment is given. The earlier oestrus after two cloprostenol injections may be due to the greater number of heifers at days 7, 8 and 9 of the oestrous cycle at the time the second injection is given.     

Contribution of dynamic calibration to the measurement accuracy of a pressure plate system throughout the stance phase in sound horses

The aim of this study was to evaluate the accuracy of the vertical force curve of a pressure plate (PP) using dynamic calibration with a force plate (FP) in six sound Warmblood horses. The animals were walked and trotted over a combined PP-FP system sampling at 250Hz. Five valid measurements of each forelimb were collected. The recalibration factor (RF), the ratio between the calibrated and raw PP data, was evaluated in each timeframe throughout the stance phase. Following dynamic calibration, the vertical force curve of the PP demonstrated a characteristic biphasic pattern at the walk and typical spikes at the beginning and end of stance at the trot. Both at walk and trot, the RF was considerably higher and more variable in the first 5% of stance (i.e. the impact phase) and during the final 20% of stance (i.e. the breakover phase), whereas between these phases (i.e. in the support phase), the RF was lower and remained relatively constant. These findings were confirmed by plotting the RF as a function of the vertical force and the RF in the loading part of the vertical force curve was lower than in the unloading part of the curve. Without dynamic calibration with a FP, the accuracy of the PP appears suboptimal, especially at the impact and breakover phases. However, the accuracy of the PP was relatively high and constant during the support phase, and higher loading was not associated with increasing deviation. It is therefore essential to optimise PP calibration, as this may downsize systematic measuring errors. However, in a clinical setting, where a stand-alone PP is used to objectively quantify locomotor symmetry, these errors can be readily eliminated by evaluating left:right symmetry ratios.     

A new method for detecting the abomasal position and characteristics of movement at the onset of the left displacement of the abomasum in cows

A new method has been developed by us to observe the movements of the abomasum by using a magnet and digital magnetometer. Four cows with left displacement of the abomasum underwent conventional correction by rolling without tacking. A doughnut-type magnet was sutured to the pyloric region in a routine operation. The same was done in three control cows. The position of the pyloric region was observed with a digital magnetometer from outside the cow's body. The magnets in the pyloric region of the control cows were located at the right side of the abdominal cavity at 10-30 cm anterior to the udder base, and moved slightly in various directions within the span of a day. On the other hand, the magnets in the pyloric region of cows with abomasal displacement moved widely in the abdominal cavity from the normal right side to the abnormal left front side. A large movement of the magnet from the normal right side to the abnormal left side of the abdominal cavity was observed within 12 h of the onset of abomasal displacement.     

Time of onset of post-partum luteal function and conception in dairy cows.

The following reproductive parameters were studied in 40 Icelandic dairy cows on 2 farms with free stall and tie stall housing: The time of onset of post-partum luteal activity; the time of first post-partum artificial insemination (AI); the time of conception; conception rate to first post-partum AI; the number of AI's per conception; length of gestation; and the number of days between 2 consecutive calvings. Milk for progesterone analysis was sampled 3 times a week from calving until first AI on farm 1, but every day for 90-100 days from calving on farm 2. In this study the average onset of luteal function was 21 days post-partum, the cows were inseminated 62 days and conceived 74 days post-partum. Conception rate to first AI was 71% and number of AI's per conception was 1.6. Significant differences were not found between the 2 farms. The reproductive performance of the cows in this study was greater than found in earlier studies of the Icelandic dairy cows and indicate that this animal has reproductive capabilities comparable to high producing foreign dairy cows.     

Correlation between age at neutering and age at onset of hyperadrenocorticism in ferrets

OBJECTIVE: To determine prevalence of hyperadrenocorticism in ferrets in The Netherlands and evaluate age, sex, and age at neutering in affected ferrets. DESIGN: Prevalence survey and retrospective study. ANIMALS: 50 ferrets with hyperadrenocorticism and 1,267 ferrets without hyperadrenocorticism. PROCEDURE: A questionnaire was sent to 1,400 members of a ferret-owners organization in The Netherlands; 492 (35%) owners returned the questionnaire, providing usable data on 1,274 ferrets. Seven of these ferrets developed hyperadrenocorticism during the survey period; medical records for these ferrets and 43 ferrets with confirmed hyperadrenocorticism were reviewed. Hyperadrenocorticism was confirmed by histologic examination of an excised adrenal gland (92% of ferrets) or clinical improvement after excision. RESULTS: Prevalence of hyperadrenocorticism in the survey population was 0.55%. Sex was not associated with prevalence of disease. Median time interval between neutering and diagnosis of hyperadrenocorticism was 3.5 years. A significant linear correlation between age at neutering and age at time of diagnosis was detected. CONCLUSIONS AND CLINICAL RELEVANCE: Age at neutering may be associated with age at development of hyperadrenocorticism in ferrets.     

Use of gyroscopic sensors for objective evaluation of trimming and shoeing to alter time between heel and toe lift-off at end of the stance phase in horses walking and trotting on a treadmill

OBJECTIVE: To determine whether a shoe with an axialcontoured lateral branch would induce greater lateral roll of the forelimb hoof during the time between heel and toe lift-off at end of the stance phase (breakover). Animals-10 adult horses. PROCEDURE: A gyroscopic transducer was placed on the hoof of the right forelimb and connected to a transmitter. Data on hoof angular velocity were collected as each horse walked and trotted on a treadmill before (treatment 1, no trim-no shoe) and after 2 treatments by a farrier (treatment 2, trim-standard shoe; and treatment 3, trim-contoured shoe). Data were converted to hoof angles by mathematical integration. Breakover duration was divided into 4 segments, and hoof angles in 3 planes (pitch, roll, and yaw) were calculated at the end of each segment. Multivariable ANOVA was performed to detect differences among treatments and gaits. RESULTS: Trimming and shoeing with a shoe with contoured lateral branches induced greater mean lateral roll to the hoof of 3.2 degrees and 2.5 degrees during the first half of breakover when trotting, compared with values for no trim-no shoe and trim-standard shoe, respectively. This effect dissipated during the second half of breakover. When horses walked, lateral roll during breakover was not significantly enhanced by use of this shoe. CONCLUSIONS AND CLINICAL RELEVANCE: A shoe with an axial-contoured lateral branch induced greater lateral roll during breakover in trotting horses, but change in orientation of the hoof was small and limited to the first half of breakover.     

Effects of an S6 strain of Mycoplasma gallisepticum challenge at onset of lay on digestive and reproductive tract characteristics in commercial layers

Mycoplasma gallisepticum (MG), a reproductive/respiratory pathogen in poultry, has been implicated in suboptimum egg production and decreased hatchability. Commercial layer hens raised in a controlled environment were inoculated with the S6 strain of MG at 20 wk of age. The S6 inoculation had no effect on bird weight, egg production, digestive tract weight and length, or histopathologic lesion scores, although significant differences were noted in the lengths and weights of various portions of the reproductive tract. This study shows that S6MG inoculation does not detrimentally affect layer hen performance when in the absence of environmental stressors customary to a caged layer facility.     

Immunoglobulin concentrations in serum and nasal secretions of calves at the onset of pneumonia

Immunoglobulin (Ig) concentrations in serum and in nasal secretions were correlated with pneumonia and diarrhea during the first 12 weeks of life in 56 calves. The peak onset of pneumonia occurred between 2 and 4 weeks of age when the calves' serum IgG1, IgG2, and IgA concentrations were lowest. As IgG2 concentrations increased, fewer calves developed pneumonia. Peak onset of pneumonia was also correlated with the lowest IgG and IgA concentrations in the calves' nasal secretions. Most calves developed pneumonia when serum concentrations of IgG1 were less than 1.5 g/dl, IgG2 less than 0.3 g/dl, IgA less than 0.1 g/dl, and IgM less than 0.2 g/dl and when the combined IgG and IgA values in nasal secretions were less than 0.2 mg of Ig/mg of protein. In study A, diarrhea preceded pneumonia in 63% of 56 calves. In study B, 38% of 23 calves had diarrhea and/or hemorrhagic feces before pneumonia. Seemingly, there was a relationship between diarrhea and pneumonia. Furthermore, pneumonia occurred at or just after the time when IgG1, IgG2, and IgA concentrations in serum and the combined IgG and IgA concentrations in nasal secretions were lowest. Pneumonia is a common disease of calves between 1 and 5 months of age, a period coinciding with the usual low point in serum immunoglobulin (Ig) concentrations due to catabolism of passively acquired antibodies. Calves that absorb less than adequate amounts of Ig may be susceptible to pneumonia at approximately 2 months of age, when serum Ig concentrations would be lowest.(ABSTRACT TRUNCATED AT 250 WORDS)     

Teladorsagia circumcincta egg output at the onset of natural and induced lactation in ewes

Nineteen ewes maintained under 'worm-free' conditions received anthelmintic and 1 week later were dosed on 5 days each week with 500 Teladorsagia circumcincta larvae for between 10 and 12.5 weeks. Faecal egg counts were determined twice weekly. There were three groups: pregnant (P) ewes (n = 6) which each reared twin lambs, hormone-treated (H) ewes (n = 7) which were not pregnant and were given exogenous hormones (dexamethasone, oestradiol-17 beta, progesterone) for 37 days to induce udder development and milk production, and untreated barren (B) ewes (n = 6). The plasma concentrations of oestradiol-17 beta, prolactin and progesterone were measured. Starting 10-15 days before birth in Group P, there was a biphasic periparturient rise in egg count and the onset of the first peak in egg count preceded the parturient peak in plasma prolactin concentration by several days. Most Group H (5/7) and all Group B ewes remained highly resistant to Teladorsagia infection throughout, despite an induced rise in prolactin concentrations in Group H ewes. It was concluded that factors other than prolactin initiate the periparturient rise but that prolactin is one factor which maintains the response once lactation commences.     

裂解酶LysGH15的CHAP片段与底物互作的关键位点

金黄色葡萄球菌噬菌体裂解酶LysGH15对金葡菌表现出广谱高效的抗菌活性,本课题组已深入研究其三维结构,其中CHAP片段是LysGH15起催化作用的关键活性片段。本试验进一步通过分子模拟和对接的方法预测出CHAP与底物多肽DGlnNH2-LLys-DAla-5Gly结合的"口袋"结构,该结构由D33、S35、F36、Y50、R71、T72及N75这些氨基酸位点组成。由于脂肪族非极性氨基酸丙氨酸侧链最短且不带电荷,因此将这些位点均突变为丙氨酸,逐一研究它们对CHAP片段催化活性的影响:圆二色谱试验结果说明突变体二级结构并未发生变化;酶谱试验结果定性的说明F36突变为丙氨酸后突变体蛋白F36A的活性完全丧失,而其他位点的氨基酸突变后蛋白活性并未发生明显改变;细菌浊度测定和菌落计数试验进一步证明突变体F36A活性完全丧失,而其他突变体活性不变;鉴于F36位于"口袋"结构的"口"的部位,36位氨基酸很可能参与到CHAP与底物多肽的结合。本试验鉴定了LysGH15的CHAP与底物多肽互作过程中起关键作用的氨基酸位点。     

苜蓿假盘菌与苜蓿叶片亲和性互作的超微结构特征

从细胞角度揭示苜蓿假盘菌与苜蓿叶片亲和性互作机制。以两者亲和性互作系统为研究材料,利用透射电子显微镜技术研究了苜蓿假盘菌与苜蓿叶片亲和性互作的超微结构特征。结果表明,病菌侵入寄主组织后,菌丝直接穿透寄主细胞壁进入寄主细胞形成胞内菌丝,以胞内生长并向相邻细胞扩展。病菌菌丝穿透寄主细胞壁时,菌丝中的液泡给予了较大的压力帮助其穿透。进入寄主细胞内的病菌菌丝,被内陷的寄主原生质膜包裹,菌丝与质膜始终是隔离的,寄主原生质膜和细胞壁之间沉积电子致密度深的物质。病菌菌丝不断地在寄主原生质膜区域扩展,伴随菌丝体在寄主细胞内的不断扩大,周围的原生质膜也相应扩大其面积,但始终将寄主原生质与菌丝体隔开,而脱离质膜的菌丝形成菌丝鞘包裹。随侵染程度的增加,未被穿透的寄主原生质膜区域逐步被降解。病菌侵染叶绿体等细胞器时,首先是菌丝鞘与叶绿体等细胞器膜相连,然后降解其基粒片层结构,被降解的细胞器组织沿菌丝和胞壁周围沉积。侵染后期,菌丝胞内和胞外扩展,但处在细胞降解物中的菌丝显示较厚的细胞壁,寄主细胞内充满了大量的黑色物质和结晶状的颗粒物。     

企业不同成长阶段的创新策略

按照企业的生命周期理论，科技型中小企业的成长过程具有阶段性的特征。为此，我们分别从技术创新、管理创新、制度创新和市场创新几方面入手来探讨渐进性创新与突破性创新在企业成长的各个阶段中所扮演的角色和科技型中小企业应采取的策略。     

介绍五种肉种鸡开产后的增料方法

当肉种鸡产蛋率达到5％以后需要及时地增加喂料量,促进产蛋率顺利地达到最高峰。这—阶段的增料方法比较重要,而各场之间差别很大。现介绍六年来的经验给同行,供参考。 用预定高峰料量减去5％产蛋率时的料量即今后后的总增料量。预定高峰料量为170克,产蛋率5％时的料量为132克,则总增料量为38克。把这38克料量在产蛋上升最快的阶段内及时恰当地加上:     

Molecular characteristics of porcine Fas-associated death domain (FADD) and procaspase-8

To reveal the intracellular signal transduction molecules involved in granulosa cell apoptosis in porcine ovarian follicles, we cloned the porcine Fas-associated death domain (FADD), an adaptor protein for the cell death receptor, and procaspase-8, an initiator caspase. Porcine FADD (pFADD) was 636 bp (211 amino acids: aa) long and showed 74.0 and 65.4% homology with human and murine FADD, respectively. Porcine procaspase-8 (pprocaspase-8) was 1,431 bp (476 aa) long and 70.6 and 63.4% homologous with human and murine procaspase-8, respectively. To confirm the apoptosis-inducing abilities, we constructed pFADD and pprocaspase-8 cDNA expression vectors with enhanced green fluorescence protein (EGFP) and then transfected them into human uterine cervix tumor (HeLa-K), human granulosa cell-derived (KGN), murine granulosa-derived tumor (KK1), and porcine granulosa cell-derived (JC410) cells. When pFADD and pprocaspase-8 were overexpressed, cell death was induced in these transfected cells. However when caspase-inhibitor p35 was cotransfected, cell death was inhibited. The pFADD and pprocaspase-8 genes are well conserved, as are the physiological functions of their products.     

Pig characteristics associated with mortality and light exit weight for the nursery phase

One thousand and ten weaned pigs that were reared in 1 nursery in Iowa from weaning (17 +/- 2 days ) until 10 weeks of age were evaluated. A weaning weight threshold of 3.6 kg maximized the sensitivity and specificity to correctly predict the likelihood of dying or being light in weight at exit from the nursery (< or = 14.5 kg). Weaning weight < or = 3.6 kg (OR = 2.92), barrow (OR = 1.75), and sow unit (A versus B, OR = 2.14) were significant predictors of mortality in the nursery. Birth weight < or = 1.0 kg (OR = 2.66), weaning weight < or = 3.6 kg (OR = 8.75), gilt (OR = 1.4), sow unit (OR = 2.38), and gilt as nursing sow at weaning (OR = 1.66) were significant predictors of being lightweight at nursery exit. Eighteen per cent of the nursery deaths and almost half of lightweight nursery pigs could be prevented if there were no lightweight pigs at weaning.     

Biomechanical analysis of the canine hind limb: calculation of forces during three-legged stance

This paper presents a three-dimensional biomechanical model of the canine hind limb, and describes the process of determining the muscle forces and joint reaction forces and moments occurring in the hind limb during three-legged stance. The model was based on anatomical and morphometric data presented in a previous paper. Equations of equilibrium were formulated for the different components of the hind limb. Since the number of unknowns exceeded the number of equations, the problem was statically indeterminate.Two optimization techniques were applied to solve this statically indeterminate problem. The resultant hip-joint reaction force (acting on the acetabulum) predicted by these optimization methods ranged between 0.73 and 1.04 times body weight, and was directed dorsally, medially and caudally. The resultant knee-joint reaction force (acting on the femur) ranged between 1.05 and 1.08 times body weight, and was directed dorsally, laterally and cranially. The largest muscle forces predicted by the minimization of maximal muscle stress (MMMS) criterion were in the biceps femoris (0.24 times body weight), rectus femoris (0.15 times body weight), medial gluteal (0.18 times body weight), semi-membranosus (0.09 times body weight), the lateral and intermediate vastus (0.18 times body weight) and the medial vastus (0.17 times body weight). The largest muscle forces predicted by the minimization of the sum of muscle forces (MSMF) criterion were in the biceps femoris (0.29 times body weight), lateral and intermediate vastus (0.45 times body weight)), and the deep gluteal (0.16 times body weight).The magnitudes and directions of the forces in the joints of the canine hind limb, as well as in the muscles that surround these joints, provide a database needed for future biomechanical analyses of the physiology and pathophysiology of the canine hind limb.     

Lamellar pro-inflammatory cytokine expression patterns in laminitis at the developmental stage and at the onset of lameness: innate vs. adaptive immune response

REASONS FOR PERFORMING STUDY: Recent research has indicated that inflammation plays a role in the early stages of laminitis and that, similar to organ failure in human sepsis, early inflammatory mechanisms may lead to downstream events resulting in lamellar failure. Characterisation of the type of immune response (i.e. innate vs. adaptive) is essential in order to develop therapeutic strategies to counteract these deleterious events. OBJECTIVES: To quantitate gene expression of pro-inflammatory cytokines known to be important in the innate and adaptive immune response during the early stages of laminitis, using both the black walnut extract (BWE) and oligofructose (OF) models of laminitis. METHODS: Real-time qPCR was used to assess lamellar mRNA expression of interleukins-1beta, 2, 4, 6, 8, 10, 12 and 18, and tumour necrosis factor alpha and interferon gamma at the developmental stage and at the onset of lameness. RESULTS: Significantly increased lamellar mRNA expression of cytokines important in the innate immune response were present at the developmental stage of the BWE model, and at the onset of acute lameness in both the BWE model and OF model. Of the cytokines characteristic of the Th1 and Th2 arms of the adaptive immune response, a mixed response was noted at the onset of acute lameness in the BWE model, whereas the response was skewed towards a Th1 response at the onset of lameness in the OF model. CONCLUSIONS: Lamellar inflammation is characterised by strong innate immune response in the developmental stages of laminitis; and a mixture of innate and adaptive immune responses at the onset of lameness. POTENTIAL RELEVANCE: These results indicate that anti-inflammatory treatment of early stage laminitis (and the horse at risk of laminitis) should include not only therapeutic drugs that address prostanoid activity, but should also address the marked increases in lamellar cytokine expression.     

妊娠母猪分阶段饲养

母猪妊娠期中的每一天均是不一样的。每一天都标志着未出生仔猪的生长进一步加快—理论上,每一天都需要一套新的营养方案。通过将妊娠期分为三个阶段,母猪的营养需求能够被更清楚地详细定义:它们需要什么?